Continuous paper feeding device and printer incorporating the same

ABSTRACT

A tractor feeds a perforated continuous paper sheet to a printing position. The feeding force of a fusing device located downstream of the printing position is set larger than the feeding force of the tractor in order to apply tension to the continuous paper sheet at the printing position. A braking device located upstream of the tractor applies a braking force balancing with the feeding force of the fusing device to the continuous paper sheet. The braking force of the braking device is varied depending upon the properties of the paper sheet or the environmental conditions. This arrangement makes it possible to stabilize the feeding state even under situations where the sheet feeding force is likely to become unstable, thereby realizing printing without any deviation from the predetermined position. Further, this arrangement can also prevent hole breakage to occur.

RELATED APPLICATIONS

The present application claims priority to Japanese Patent ApplicationNo. 2000-259553 filed Aug. 29, 2000, the entire content of which ishereby incorporated by reference.

TECHNICAL FIELD OF THE INVENTION

This invention relates to continuous paper feeding devices for feedingcontinuous paper sheets, and in particular, to printers for printingimages on perforated printing paper sheets.

BACKGROUND OF THE INVENTION

Conventional printers adapted for printing on continuous paper sheetsemploy a tractor feeder which is capable of horizontally feedingprinting paper sheets as a feeding device for feeding continuous papersheets in order to realize their downsizing. The tractor feeder isconfigured to feed a printing paper sheet by causing feed pins of arotary-driven endless tractor to sequentially engage perforationsarranged with a predetermined pitch longitudinally of the printing papersheet.

As is often the case with such continuous paper printers, the feedingdevice is located upstream of the printing device (the printing deviceincluding, for example, a photosensitive drum and the like), whileanother feeding device (such as fusing rollers) is located downstream ofthe printing device. In this case, it is common practice to set thefeeding speed of the downstream feeding device to be slightly higherthan that of the tractor. This allows a printing paper sheet underfeeding to be brought into close contact with the printing device. Forthis reason, the tension on the peripheral edge of each perforation isexcessive when compared to the rest of the printing paper sheet underfeeding. Hence, “hole breakage”, which is a perforation enlargingphenomenon, is likely to occur. The occurrence of heavy hole breakageresults in feeding the printing paper sheet, thereby causing a deviationfrom the predetermined printing position.

Japanese Patent Laid-Open Gazette No. HEI 7-215551 discloses acontinuous paper feeding device incorporating a load imposing mechanismlocated upstream of the tractor for exerting a constant braking force onthe printing paper sheet to prevent an excessive tensile stress fromworking on the peripheral edge of each perforation.

The continuous paper feeding device disclosed in this Gazette applies aconstant braking force to the printing paper sheet, as described above.For this reason, if the balance between the feeding forces respectivelyworking on the upstream and downstream sides of the feeding device, suchas the tractor, is lost even slightly, a deviation in the positioning ofthe paper sheet relative to the photosensitive drum occurs due to suchan imbalance, thus resulting in a lowered precision in positioning forprinting.

SUMMARY OF THE INVENTION

The present invention provides a continuous paper feeding device havinga higher feeding precision.

The present invention also provides a continuous paper feeding devicewhich is free from the hole breakage problem.

The present invention also provides a printer which is capable ofprinting on a continuous paper sheet with a higher positioningprecision.

In one embodiment of the invention, there is a continuous paper feedingdevice for feeding a perforated continuous paper sheet. The deviceincludes, for example, a paper supply device configured to supply thecontinuous paper sheet; a tractor configured to feed the continuouspaper sheet supplied from the paper supply device while engagingperforations of the continuous paper sheet; a braking device locatedbetween the paper supply device and the tractor and configured to applya braking force to the continuous paper sheet; a braking force settingdevice for setting the braking force; and a controller for controllingthe braking force applied by the braking device according to the settingmade by the braking force setting device.

With this continuous paper feeding device, when a continuous printingpaper sheet supplied from the paper supply device is fed by the tractor,the controller controls the braking force applied by the braking deviceaccording to the braking force set by the braking force setting device.Accordingly, a high feeding precision can be ensured because thecontinuous paper sheet is applied with an optimized braking force, evenunder such situations as to cause the paper feeding force to becomeunstable. Further, it is possible to inhibit the occurrence of holebreakage.

In another embodiment of the invention, there is a printer for printingan image onto a perforated continuous paper sheet. The printer includes,for example, a paper supply device configured to supply the continuouspaper sheet; a tractor configured to feed the continuous paper sheetsupplied from the paper supply device while engaging perforations of thecontinuous paper sheet; a printing device configured to print the imageonto the continuous paper sheet at a location downstream of the tractor;a braking device located between the paper supply device and the tractorand configured to apply a braking force to the continuous paper sheet; abraking force setting device for setting the braking force; and acontroller for controlling the braking force applied by the brakingdevice according to the setting made by the braking force settingdevice.

The printer of the above construction is capable of printing images ontoa continuous paper sheet with a high positioning precision. The feedingspeed on the downstream side of the printing device is desirably madehigher than that of the tractor to prevent the continuous paper sheetfrom slackening at a location adjacent the printing device. Even in thiscase, the balance between the feeding forces respectively working on theupstream and downstream sides of the tractor can be maintained by thebraking force applied by the braking device, thereby ensuring a highprint position precision.

The invention itself, together with further objects and attendantadvantages, will best be understood by reference to the followingdetailed description taken in conjunction with the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view showing a principal portion of a continuouspaper feeding device as a first embodiment of the present invention.

FIG. 2 is a perspective view showing a tractor of the continuous paperfeeding device.

FIG. 3 is a partially cutaway perspective view showing a braking deviceof the continuous paper feeding device.

FIG. 4 is a sectional view taken along line IV-IV in FIG. 3.

FIG. 5 is a front elevational view showing a brake value setting picturepresented by a setting panel.

FIG. 6 is a diagram showing the relationship between a braking force anda set brake value.

FIG. 7 is a flowchart of an operational sequence of the continuous paperfeeding device.

FIG. 8 a is a table showing a set brake value corresponding to a brakingforce for each paper sheet thickness.

FIG. 8 b is a table showing a set brake value corresponding to a brakingforce for each paper sheet width.

FIG. 8 c is a table showing a set brake value corresponding to a brakingforce for each humidity degree of a printer-installed environment.

FIG. 9 is a perspective view showing a principal portion of a continuouspaper feeding device as a second embodiment of the present invention.

FIG. 10 is a perspective view showing a principal portion of acontinuous paper feeding device as a third embodiment of the presentinvention.

FIG. 11 is a perspective view showing a principal portion of acontinuous paper feeding device as a fourth embodiment of the presentinvention.

FIG. 12 a illustrates a perforation free of hole breakage.

FIG. 12 b illustrates a perforation with hole breakage at its peripheraledge on the upstream side.

FIG. 12 c illustrates a perforation with hole breakage at its peripheraledge on the downstream side.

FIG. 13 a illustrates a perforation free of hole breakage.

FIG. 13 b illustrates a perforation with hole breakage at its peripheraledge on the upstream side.

FIG. 13 c illustrates a perforation with hole breakage at its peripheraledge on the downstream side.

In the following description, like parts are designated by likereference numbers throughout the several drawing.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention will now be described in detail by way ofembodiments thereof with reference to the drawings.

FIG. 1 is a perspective view showing a continuous paper feeding deviceas a first embodiment of the present invention. In FIG. 1, continuouspaper feeding device A is incorporated in a laser printer. Thecontinuous paper feeding device A comprises a paper supply section 20 asa paper supply device, a feeding section 2 adapted to feed a continuousprinting paper sheet 1 supplied from the paper supply section 20, aprinting device 3 disposed downstream of the feeding section 2, a fusingsection 4 located downstream of the printing device 3, a braking device19 disposed upstream of the feeding section 2, a motor control section 7for controlling a fan motor of the braking device 19, and a CPU 10 forcontrolling each section.

The paper supply section 20 accommodates the printing paper sheet 1 in afolded state, the paper sheet 1 having perforated lines P along whichthe paper sheet 1 can be cut at predetermined longitudinal intervals.

When the printing paper sheet 1 (set on the feeding section 2) receivesa feeding force, the printing paper sheet 1 is delivered our of thepaper supply section 20 in a direction indicated by arrow a. As bettershown in FIG. 2, the printing paper sheet 1 has one widthwise sideportion defining multiple perforations 11 arranged in a row, with apredetermined pitch longitudinally of the paper sheet 1. Theseperforations 11 are sequentially engageable and disengageable with feedpins (described below).

The printing device 3 has a photosensitive drum 22, a transfer roller 13in rotary contact with the photosensitive drum 22, and the like. A tonerimage is formed on the photosensitive drum 22 according to image data byan exposure system (not shown) and a developing device 22 a and thentransferred to a surface of the printing paper sheet 1.

The fusing section 4 has a pair of fusing rollers 4 a and 4 b pinchingand rotary-contacting the printing paper sheet 1 thicknesswise thereof,and functions to fuse the toner image onto the printing paper sheet 1 byheating and pressurizing the printing paper sheet 1. The fusing rollers4 a and 4 b apply a feeding force to the printing paper sheet 1 becauseof their rotary contact with the printing paper sheet 1. The feedingspeed at this point is therefore slightly higher than that at thefeeding section 2. The printing paper sheet 1 is thus prevented fromslackening at a location adjacent to the printing position of theprinting device 3, thus ensuring favorable transfer of the toner imagefrom the photosensitive drum 3 to the printing paper sheet 1.

As shown in FIG. 2, the feeding section 2 comprises a tractor feederhaving an endless tractor 21 and a motor 9. The tractor 21 is trainedbetween and around a driving wheel 21 a and a driven wheel 21 b, and hasone widthwise side portion having feed pins 12 for engagement with theaforementioned perforations 11. The tractor 21 revolves with rotation ofthe driving wheel 21 a (driven by the motor 9) with the feed pins 12disengageably engaging the corresponding perforations 11 of the printingpaper sheet 1 in sequence. This results in feeding the printing papersheet 1 toward the downstream side by traction.

If a portion of the printing paper sheet 1 (which remains unprinted) isleft in the feeding section 2 (at the time the printing with respect tothe printing paper sheet 1 has been completed), the tractor 21 isrevolved backwards by the motor 9 to return the unprinted portion of theprinting paper sheet 1 to the paper supply section 20.

The braking device 19 functions to provide a variable braking forceagainst the feeding force applied to the printing paper sheet 1 by thefusing section 4. The braking device 19, as shown in FIGS. 3 and 4,includes a brake case 5 disposed to face the reverse side of theprinting paper sheet 1, an evacuation fan 19 a for producing a negativepressure in the brake case 5 by evacuating the brake case 5, and a fanmotor 6 for driving the evacuation fan 6. The brake case 5 has an upperwall surface serving as a guide surface 14 for guiding the printingpaper sheet 1. The guide surface 14 comprises a perforated platedefining a multiplicity of air-suction perforations.

A guide roller 18 is disposed adjacent to the braking device 19, on theupstream side thereof. The guide roller 18 guides the printing papersheet 1 so that the sheet 1 is brought into intimate sliding contactwith the upper surface 14 of the brake case 5.

A negative pressure is produced in the brake case 5 by evacuation whenthe printing paper sheet 1 passes the guide surface 14 of the brakingdevice 19. Hence, a suction force is exerted on the printing paper sheet1 through the air-suction perforations 15. In this way, the printingpaper sheet 1 is applied with a braking force produced by the slidingresistance between the printing paper sheet 1 and the guide surface 14.

As shown in FIGS. 3 and 4, a partition plate 19 b is provided within thebrake case 5 to adjust the width of the internal space of the brake case5, according to the width W of the printing paper sheet 1. Attached tothe partition plate 19 b is a thumbscrew 19 d which protrudes upwardlyoutwardly from the brake case 5 through a guide slot 19 c defined in theguide surface 14. The guide slot 19 c extends widthwise of the printingpaper sheet 1 (in the direction indicated by arrow b) to allow thethumbscrew to shift along the guide slot 19 c, thereby allowing thepartition plate 19 b to shift widthwise of the printing paper sheet 1.Specifically, the thumbscrew 19 d is moved to position the partitionplate 19 b to a location depicted by the chain line in FIG. 4 when thewidth W of the printing paper sheet 1 is larger. Alternatively, thethumbscrew 19 d is moved to position it to a location depicted by thesolid line when the width W of the printing paper sheet 1 is smaller.This arrangement causes a suction force to effectively work on theprinting paper sheet 1 within a space having a width adjusted to thewidth of the printing paper sheet 1.

The CPU 10 controls the operation of the motor 9 of the feeding section2, sets a braking force according to a set brake value input from asetting panel 8, and controls the motor control circuit 7. The motorcontrol circuit 7 controls revolutions of the evacuation fan 6 toprovide a braking force according to the setting.

FIG. 5 is a front elevational view of the setting panel 8. The settingpanel 8 is capable of displaying a “SUCTION BRAKE SETTING” picture 8 a(as shown in the drawing) on an LCD panel that is operable by touch. Forthe user to become capable of inputting a desired set brake value, thepicture 8 a has a set brake value display section 8 b for displaying anyone of integers from 1 to 8, an up key (▴ key) 8 c for displaying alarger integer in the set brake value display section 8 b, a down key (▾key) 8 d for displaying a smaller integer in the set brake value displaysection 8 b, and a return key 8 e for setting the integer displayed inthe set brake value display section 8 b as a set brake value.

In selecting a desired set brake value, the user causes the displaypanel to display the “SUCTION BRAKE SETTING” picture 8 a, presses eitherthe up key (▴ A key) 8 c to increase the set brake value or the down key(▾ key) 8 d to decrease the set brake value, and presses the return key8 e when the desired set brake value is determined.

FIG. 6 shows the relationship between set brake value x and brakingforce y. The CPU 10 controls the motor control circuit 7, based on setbrake value x input from the setting panel 8, so that braking force yplotted by the alternate long and short dash line in FIG. 6 is obtained.Braking force y plotted by the alternate long and short dash line isdefined by the following formula:y=0.0994×−0.0172

It should be noted that the solid line plots measured braking forcesactually obtained.

The principal operation of the continuous paper feeding device A shownin FIG. 1 is described below with reference to the flowchart shown inFIG. 7.

First, the printing paper sheet 1 delivered out of the paper supplysection 20 is set on the feeding section 2, so that the perforations 11of the paper sheet 1 engage the corresponding feed pins 12 of thetractor 21 (step 101). With the printing paper sheet 1 in this state,the fusing rollers 4 a and 4 b are actuated while, on the other hand,the motor 9 of the feeding section 2 is driven to cause the tractor 21to revolve. As the tractor 21 revolves, the printing paper sheet 1 isfed toward the printing device 3 (102). Thereafter, the fan motor 6 iscaused to rotate (201).

In the printing device, a toner image on the photosensitive drum 3 istransferred onto the printing paper sheet 1 by the transfer roller 13.Thereafter, the printing paper sheet 1 is fed toward the fusing section4 (103) where the toner image is fused to the printing paper sheet 1.

Tension resulting from the feeding force of the fusing rollers 4 a and 4b is not exerted on the printing paper sheet 1 during the passage of theprinting paper sheet 1 up to the fusing section 4 through the printingdevice 3. Hence, any stress is not imposed on the perforations 11 duringthis period because the paper sheet 1 is fed by the feeding section 2.Accordingly, there is no need to apply any braking force to the printingpaper sheet 1 on the upstream side of the feeding section 2. However,taking into account that there is a time lag between the actuation ofthe fan motor 6 and the buildup of a negative pressure in the brake case5, the fan motor 6 is preferably actuated before the printing papersheet 1 reaches the fusing section 4.

As described above, the feeding speed of the pair of fusing rollers 4 aand 4 b is established so as to be slightly higher than that of thefeeding section 2. Hence, a tensile force toward the downstream side isapplied to the printing paper sheet 1 on the tractor 21 after the papersheet 1 has reached the fusing section 4. This results in a tensilestress is imposed on the perforations 11 (103).

At this time, the brake case 5 of the braking device 19 is evacuated bythe fan motor 6, a negative pressure is produced within the brake case 5and applied to the printing paper sheet 1 passing the guide surface 14of the brake case 5 (202). Accordingly, a suction force is exerted onthe reverse side of the printing paper sheet 1 through the air-suctionperforations 15. At the same time, the atmospheric pressure is workingon the obverse side of the paper sheet 1. Thus, the printing paper sheet1 is fed as pressed against the guide surface 14 of the brake case 5.

When the printing on the printing paper sheet 1 has been completed(104), the rotation of the fusing rollers 4 a and 4 b and the feeding ofthe printing paper sheet 1 are stopped. The revolution of the fan motor6 is also stopped (203). The user can then cut off the printing papersheet 1 printed with an image fused thereto at a given perforation lineP.

Thereafter, if an unprinted portion of the printing paper sheet 1 isleft at the feeding section 2, the unprinted portion is returned to thepaper supply section 20 by causing reverse rotation of the motor 9 ofthe feeding section 2 (105). At this time, a negative pressure is nolonger produced within the brake case 5 due to stoppage of the fan motor6. Hence, the braking force applied to the printing paper sheet 1 isreleased (204). Accordingly, the printing paper sheet 1 is smoothlyreturned to the paper supply section 20 while sliding on the guidesurface 14 without being pressed against the guide surface 14.

In the embodiment described above, the sliding resistance according tothe coefficient of friction between the printing paper sheet 1 and thebrake case 5 functions as a braking force. Accordingly, the feedingtension exerted on the printing paper sheet 1, on the downstream side ofthe feeding section 2 (on the paper ejecting side), and that exerted onthe paper sheet 1 (on the upstream side of the feeding section) arebalanced. As a result, the tensile stress imposed on the feed pins 12 ofthe feeding section 2, and on the perforations 11 of the printing papersheet 1, is suppressed. The occurrence of hole breakage acting toenlarge the perforations 11 is prevented in this way.

Further, the motor control circuit 7 controls revolutions of the fanmotor 6 according to the braking force set by the CPU 10. This causesthe braking device 19 to apply an optimized braking force to theprinting paper sheet 1. Accordingly, even when the paper feeding forceis unstable, the braking force is adjusted to accommodate the situation.Hence, the tension applied to the printing paper sheet 1 is madeconstant to ensure stabilized feeding. In this way, the positionalprecision of the printing paper sheet 1 relative to the printing device3 can be maintained favorably.

Furthermore, since the braking device 19 is constructed of suctionmeans, the printing paper sheet 1 is not damaged when applied with thebraking force.

Although the foregoing embodiment is configured to have the user input aset brake value, the continuous paper feeding device may also beconfigured to have the user input the properties of a printing papersheet 1, such as thickness t or width w, and the environmentalconditions, such as the humidity of the atmosphere around theinstallation site. FIG. 8 a is a table showing an example of a set brakevalue corresponding to a braking force for each paper sheet thickness t,FIG. 8 b is a table showing an example of a set brake valuecorresponding to a braking force for each paper sheet width w, and FIG.8 c is a table showing an example of a set brake value corresponding toa braking force for each humidity degree of a printer-installedenvironment. These set brake values are previously stored in table formin a storage device incorporated in the printer. Referring to FIG. 8 a,when the user inputs, for example, 58 as the paper sheet thickness, theCPU references the table stored in the storage device and establishes aset brake value of 7. Once the set brake value of 7 has beenestablished, the CPU sets braking force y calculated according to theaforementioned formula as in the foregoing embodiment.

By configuring the continuous paper feeding device, so as to have theuser input the properties of a printing paper sheet or the environmentalconditions as described above, feeding forces respectively working onthe upstream and downstream sides of the feeding section 2 are balancedwithout being influenced by any change in the type of paper sheet or inthe conditions of the installation environment. Thus, the continuouspaper feeding device is capable of feeding printing paper sheet 1 in aconstantly stabilized state, thereby assuredly preventing deviations ofthe printing position.

The continuous paper feeding device may be configured to have the userinput a specific value as one of the properties of a printing papersheet to be used or as one of the environmental conditions.Alternatively, it may be configured to have the user select one ofpredetermined levels of a sheet property or an environmental condition,such as “HIGH”, “MEDIUM” and “LOW”.

FIG. 9 illustrates a continuous paper feeding device as a secondembodiment of the present invention. Like or corresponding parts aredesignated by like reference numbers throughout FIGS. 1 and 9 to avoidrepetition of description thereof.

While the embodiment shown in FIG. 1 is configured to set a brakingforce to be applied by the braking device 19 according to data inputfrom the setting panel by the user, the embodiment shown in FIG. 9 isconfigured to cause the CPU to set a braking force automatically.

Specifically, continuous paper feeding device A (shown in FIG. 9) isprovided with a sensor 23 for judging whether a paper sheet is passingand detecting sheet width W, a sensor 24 for detecting the distance upto a paper sheet and determining sheet thickness t based on the distancethus detected, and a sensor 25 for detecting the humidity of theatmosphere around the printer-installed site. CPU 10 establishes abraking force by making synthetic judgment from all the results outputfrom the sensors 23 to 25.

In this embodiment, an optimized braking force with respect to printingpaper sheet 1 is automatically established even when there is any changein the type of a paper sheet, such as sheet width W or sheet thicknesst, or in the humidity of the printer-installed environment.

It should be noted that the locations of the sheet width detectingsensor 23, sheet thickness detecting sensor 24 and the humiditydetecting sensor 25 are not limited to those shown in FIG. 9 and may bedetermined as desired. For example, it is possible that the sheet widthdetecting sensor 23 and sheet thickness detecting sensor 24 may bedisposed adjacent to the paper supply section 20.

FIG. 10 illustrates a continuous paper feeding device incorporating abraking device 39 of a different type as a third embodiment of thepresent invention. Like or corresponding parts are designated by likereference numbers throughout FIGS. 1 and 10 to avoid repetition ofdescription thereof.

The braking device 39 shown in FIG. 10 comprises a pair of brakingrollers 31 and 32 located upstream of the feeding section 2 and holdingprinting paper sheet 1 therebetween from its obverse and reverse sides.The braking roller 31 is freely rotatable as the printing paper sheet 1moves. The braking roller 32 is connected to an electromagnetic brake 33for imposing a load on the braking roller 32 rotating. Theelectromagnetic brake 33 varies the load on the braking roller 32according to its electromagnetic force varied by a current controlcircuit 43 controlling the amount of electric current.

With this arrangement, CPU 10 selects a braking force according to a setbrake value established through the setting panel 8, and the currentcontrol circuit 34 controls the amount of current passing through theelectromagnetic brake 33. In this way, the braking rollers 31 and 32provide an optimized braking force. Accordingly, the printing papersheet 1 can be applied with a braking force meeting the sheet propertiesor the environmental conditions. Hence, a stabilized feeding state ismaintained thereby ensuring a print without any deviation of theprinting position. Further, the continuous paper feeding device,according to this embodiment, has another advantage that the brakingdevice 39 is of a simplified construction because a braking forceapplied to the printing paper sheet 1 is produced by the pressing forceof the braking rollers 31 and 32.

FIG. 11 is a perspective view showing a continuous paper feeding deviceas a fourth embodiment of the present invention. Like or correspondingparts are designated by like reference numbers throughout FIGS. 1 and 11to avoid repetition of description thereof.

Continuous paper feeding device A (shown in FIG. 11) is provided withhole breakage detection means 43 comprising a hole breakage detectingsensor 41 and a hole breakage detecting circuit 42.

The hole breakage detecting sensor 41 comprises a reflection typephotosensor, the output of which becomes “ON” or “OFF” depending uponwhether it receives reflected light of light directed at the perforatedregion of printing paper sheet 1.

As shown in FIG. 12, a cylindrical non-reflective member 12 a is fittedover the peripheral portion of each feed pin 12 of the tractor 21. Thisprevents the peripheral surface of the feed pin 12 from reflecting lightemitted from the hole breakage detecting sensor 41. On the other hand, acentral portion of the top face of each feed pin 21 is provided with awhite reflective surface 12 b for reflecting light from the holebreakage detecting sensor 41.

When a perforation and a feed pin are engaged and do not face the holebreakage detecting sensor 41 (as shown in FIG. 12 a), light from thehole breakage detecting sensor 41 is reflected by a surface of thenon-perforated region of the printing paper sheet 1. The output of thehole breakage detecting sensor 41 receiving the reflected light is inthe “ON” state.

When the perforation and the feed pin engaged and are to face with thehole breakage detecting sensor 41, light from the hole breakagedetecting sensor 41 is not reflected at the peripheral portion 12 a ofthe feed pin 12. Hence, the output of the hole breakage detecting sensor41 becomes “OFF”. At the central portion of the top face of the feed pin12, light from the hole breakage detecting sensor 41 is reflected by thewhite reflective surface 12 b. Hence, the output of the hole breakagedetecting sensor 41 receiving the reflected light becomes “ON”.

In a normal state where the perforation 11 has no hole breakage (asshown in FIG. 12 a), the feed pin 12 is fitted in the perforation 11with substantially no clearance therebetween. Accordingly, the output ofthe hole breakage sensor 41 becomes “OFF” when the peripheral portion 12a of the feed pin 12 passes the sensor 41. Since the peripheral portion12 a has an equal width on diametrically opposite sides thereof, therespective periods of two “OFF” outputs obtained when one feed pin 12has passed the hole breakage detecting sensor 41 are equal to eachother.

On the other hand, in a state where the perforation 11 has hole breakageat its peripheral edge on the upstream side thereof, and a clearance gis defined downstream of the perforation 11 (as shown in FIG. 12 b), orwhere the perforation 11 has hole breakage at its peripheral edge on thedownstream side thereof and a clearance g is defined upstream of theperforation 11 (as shown in FIG. 12 c), light directed toward theclearance g from the hole breakage sensor 41 reaches a surface of thetractor 21 through the clearance g. Since the surface of the tractor 21does not reflect light, the output of the hole breakage detecting sensor41 becomes “OFF”. Accordingly, the “OFF” period of the hole breakagedetecting sensor 41 is prolonged by a time period corresponding to theclearance g. Thus, the amount of hole breakage is found from the lengthof an “OFF” period in an output waveform of the hole breakage detectingsensor 41, and the location of the hole breakage is determined fromwhether upstream or downstream of the perforation 11 a longer “OFF”period is located.

The hole breakage detecting circuit 42 forwards an information signalindicative of the amount of hole breakage to the CPU 10 upon receipt ofthe output from the hole breakage detecting sensor 41.

The CPU 10 selects a braking force suited to the type of a paper sheetused or to the printer-installed environment from a prestored table ofbrake forces on the basis of the hole breakage information received fromthe hole breakage detecting circuit 42. The CPU 10 then forwards a PWMpulse signal corresponding to the braking force thus selected to themotor control circuit 7. According to the amount of hole breakage, themotor control circuit 7 controls revolutions of the fan motor 6 so thatan appropriate braking force is applied to the printing paper sheet 1.

More specifically, when hole breakage such that clearance g is defineddownstream of the perforation 11 is detected as shown in FIG. 12 b, theCPU 10 judges that the braking force applied by the braking device 19 issmaller than the feeding force of the fusing section 4 and controls thebraking device 19 so that a larger braking force is applied. Conversely,when hole breakage such that clearance g is defined upstream of theperforation 11 is detected as shown in FIG. 12 c, the CPU 10 judges thatthe braking force applied by the braking device 19 is larger than thefeeding force of the fusing section 4 and controls the braking device 19so that a smaller braking force is applied. By so doing, the feedingforce of the fusing section 4 and the braking force of the brakingdevice 19 become well-balanced thereby preventing the hole breakage frombecoming larger, ensuring a satisfactory printing precision.

FIG. 13 illustrates hole breakage detection means of another type. InFIG. 13, the hole breakage detecting sensor 41 is disposed facing theunderside of the tractor 21. At the root of each feed pin 12, thetractor 21 defines upstream through-hole 51 and downstream through-hole52 of the same size.

In a normal state where each perforation 11 of the printing paper sheet1 has no hole breakage (as shown in FIG. 12 a), light from the holebreakage detecting sensor 41 is not reflected during a period for whicha through-hole free region on the underside of the tractor 21 faces thehole breakage detecting sensor 41. Accordingly, the output of the holebreakage detecting sensor 41 is in the “OFF” state. On the other hand,during a period for which the through-hole 51 or 52 faces the holebreakage detecting sensor 41, light from the hole breakage detectingsensor 41 passes through the through-hole 51 or 52 and is reflected bythe reverse side of the printing paper sheet 1. Accordingly, the outputof the hole breakage detecting sensor 41 assumes “ON” for a time periodfor which the sensor receives the reflected light.

In the case where there is no hole breakage, the output of the holebreakage detecting sensor 41 becomes “ON” when the upstream through-hole51 or the downstream through-hole 52 passes the sensor 41. Since the twothrough-holes are of the same size, respective periods of the two “ON”outputs obtained when one feed pin 12 has passed the hole breakagedetecting sensor 41 are equal to each other.

On the other hand, in the case where the perforation 11 has holebreakage at its peripheral edge on the upstream side thereof and aclearance g is defined downstream of the perforation 11 (as shown inFIG. 13 b), the output of the hole breakage detecting sensor 41 assumes“ON” during a time period for which light penetrating through theupstream though-hole 51 from the hole breakage detecting sensor 41 isbeing reflected by the reverse side of the printing paper sheet 1.However, this “ON” period is shortened because light from the holebreakage detecting sensor 41 is not reflected during a time period forwhich the light is passing through the clearance g. Likewise, in thecase where the perforation 11 has hole breakage at its peripheral edgeon the downstream side thereof and a clearance g is defined upstream ofthe perforation 11 (as shown in FIG. 13 c), the “ON” period of the holebreakage detecting sensor 41 is shortened because light penetratingthrough the through-hole 52 from the hole breakage detecting sensor 41is not reflected during a time period for which the light is passingthrough the clearance g. Accordingly, the “ON” period of the holebreakage detecting sensor 41 is shortened by a time period correspondingto the clearance g. Thus, the amount of hole breakage is found from thelength of an “ON” period in an output waveform of the hole breakagedetecting sensor 41, and the location of the hole breakage is determinedfrom whether upstream or downstream of the perforation 11 a shorter “ON”period is located.

The hole breakage detection means may comprise any other type of sensorthan the optical sensor 41 described above, image pick-up means or likemeans.

While the feeding section 2 is constructed of a tractor feeder in eachof the foregoing embodiments, the construction of the feeding section 2is not limited thereto.

It should be further noted that the braking device 19 or 39 may be ofany construction other than described above.

Although the present invention has been fully described by way ofexamples with reference to the accompanying drawings, it is to notedthat various changes and modifications will be apparent to those skilledin the art. Therefore, unless such changes and modification depart fromthe scope of the present invention, they should be construed as beingincluded there in.

1. A continuous paper feeding apparatus for feeding a perforatedcontinuous paper sheet, comprising: a paper supply device configured tosupply the continuous paper sheet; a tractor configured to feed thecontinuous paper sheet supplied from said paper supply device whileengaging perforations of the continuous paper sheet; a braking devicelocated between said paper supply device and said tractor and configuredto apply a braking force to the continuous paper sheet; braking forcesetting device for variably setting the braking force; and a controllerto control the variable braking force applied by the braking deviceaccording to the setting made by said braking force setting.
 2. Acontinuous paper feeding apparatus according to claim 1, furthercomprising a sensor to detect a perforation enlarging.
 3. A continuouspaper feeding apparatus according to claim 2, wherein said braking forcesetting device sets the braking force according to a detecting result ofsaid sensor.
 4. A continuous paper feeding apparatus according to claim1, wherein said braking force setting device sets the braking forceaccording to a type of the continuous paper sheet.
 5. A continuous paperfeeding apparatus according to claim 1, wherein said braking forcesetting device sets the braking force according to conditions of aninstallation environment.
 6. A continuous paper feeding apparatusaccording to claim 1, wherein said braking device includes an evacuatingdevice to evacuate the continuous paper sheet thicknesswise.
 7. Acontinuous paper feeding apparatus according to claim 1, wherein saidbraking device includes a pressurizing device to pressurize thecontinuous paper sheet thicknesswise.
 8. A printer for printing an imageonto a perforated continuous paper sheet, comprising: a paper supplydevice configured to supply the continuous paper sheet; a tractorconfigured to feed the continuous paper sheet supplied from said papersupply device while engaging perforations of the continuous paper sheet;a printing device configured to print the image onto the continuouspaper sheet at a location downstream of said tractor; a braking devicelocated between said paper supply device and said tractor and configuredto apply a braking force to the continuous paper sheet; a braking forcesetting device to set the braking force; and a controller to control thebraking force applied by said braking device according to the settingmade by said braking force setting device.
 9. A printer according toclaim 8, further comprising a sensor to detect a perforation enlarging.10. A printer according to claim 9, wherein said braking force settingdevice sets the braking force according to a detecting result of saidsensor.
 11. A printer according to claim 8, wherein said braking forcesetting device sets the braking force according to a type of thecontinuous paper sheet.
 12. A printer according to claim 8, wherein saidbraking force setting device sets the braking force according toconditions of an installation environment.
 13. A printer according toclaim 8, wherein said braking device includes an evacuating device forevacuating the continuous paper sheet thicknesswise.
 14. A printeraccording to claim 8, wherein said braking device includes apressurizing device to pressurize the continuous paper sheetthicknesswise.
 15. A printer according to claim 8, further comprising afixing device configured to fix the image onto the continuous papersheet at a location downstream of said printing device.
 16. A printeraccording to claim 15, wherein said fixing device applies tension to thecontinuous paper sheet.
 17. A continuous paper feeding apparatus,comprising: a sheet supply device configured to supply a continuousprinting paper sheet; a feeding device configured to feed the printingpaper sheet supplied from said sheet supply device; a braking deviceconfigured to apply a braking force to the printing paper sheet fed bysaid feeding device; a braking force setting device to set the brakingforce; and a controller to control the braking force applied by thebraking device according to the setting made by said braking forcesetting device.
 18. A continuous paper feeding apparatus according toclaim 17, wherein said braking device is located upstream of saidfeeding device.
 19. A continuous paper feeding apparatus according toclaim 17, further comprising a printing device configured to print theimage onto the continuous printing paper sheet fed by said feedingdevice at a location downstream of said feeding device.
 20. A continuouspaper feeding apparatus according to claim 17, said feeding deviceincludes a tractor having feed pins for engaging perforations of theprinting paper sheet.
 21. A continuous paper feeding apparatus accordingto claim 20, further comprising a sensor for detecting a perforationenlarging.
 22. A continuous paper feeding apparatus according to claim21, wherein said braking force setting device sets the braking forceaccording to a detecting result of said sensor.
 23. A continuous paperfeeding apparatus according to claim 17, wherein said braking forcesetting device sets the braking force according to a type of theprinting paper sheet.
 24. A continuous paper feeding apparatus accordingto claim 17, wherein said braking force setting device sets the brakingforce according to conditions of an installation environment.
 25. Acontinuous paper feeding apparatus according to claim 17, wherein saidbraking device includes an evacuating device to evacuate the printingpaper sheet thicknesswise.
 26. A continuous paper feeding apparatusaccording to claim 17, wherein said braking device includes apressurizing device to pressurize the printing paper sheetthicknesswise.